• Lightning protection - Getting the right surge protection

    The extensive use of electronics within industrial processes and buildings has meant  protection against the effects of voltage surges is no longer an option but has become a necessity. Lightning produces an extremely large quantity of pulsed electrical energy, which means surge protection devices designed to limit transient overvoltages need to be correctly specified to ensure they are effective. Tom France from Schneider Electric looks at the selection considerations, taking into account location and the types available

    As business operations become increasingly sophisticated, the use of technologies such as LCD screens, computer networks, data servers and industrial equipment such as programmable logic controllers, means that protection against the effects of voltage surges is crucial.

  • Upgraded lightning protection for remote corrosion monitoring

    Abriox has upgraded the lightning protection on its remote corrosion monitoring solutions for pipelines, with the help of the lightning test consultancy services of Cobham Technical Services. The degree of protection of the system against high energy surges has been substantially enhanced by a development exercise incorporating advice on the nature of coupling between lightning power surges and ground-based equipment, and characterisation studies including destructive testing.

    The protection has been implemented on Abriox's Merlin cathodic protection (CP) monitor. This telemetry-based instrument is one of the most widely used field devices for remotely monitoring the anti-corrosion CP systems that are installed on pipelines, storage tanks and other buried metal infrastructure used in onshore oil and gas networks.

    "Pipelines are a significant attractor for lightning, and in some regions of the world strikes can occur frequently. We've always had lightning protection on our corrosion monitor, but the only feedback we ever got on how it performed in the real world tended to be when a burnt-out unit arrived back from the field," says Jason Hanlon, technical director of Abriox. "How much energy was present, what the shape of the energy surge was, whether it arrived directly or indirectly remained a mystery - and we decided it would be a good idea to better understand the risk by talking with lightning experts."

    Abriox has its design centre in the UK, and after investigating the high voltage testing market, selected UK-based Cobham Technical Services, because its lightning unit is one of a tiny number of organisations in the world that specialise in lightning testing and consultancy and is able to give practical advice, rather than simply testing against standards.

    An initial review considered the particular installation conditions and environments of the Merlin CP monitor, and a typical catastrophic field failure. A destructive test at Cobham's test facility in Abingdon was performed. It became clear the corrosion monitor was most likely dealing with power surges that arrived following direct strikes on the pipeline itself, or the supply to the electrical rectifiers that provide the impressed-current cathodic protection system. Unlike some of the areas that Cobham works in - particularly aircraft protection - there are no standard lightning test waveforms for this type of nearby strike to ground-based equipment, but that did not prevent Cobham from creating a representative waveform specifically for this testing purpose.

    The destructive test exercise also demonstrated to Abriox that some of the external lightning surge protection devices originally selected for use with Merlin did not actually perform in the way the manufacturer's datasheet indicated. Although other aspects of the Merlin design provided a good degree of protection, the Abriox designers sought further improvement.

    After the exercise, Abriox gained a better understanding of the nature and energy levels of lightning-related power surges, and decided to re-engineer the system to increase the protection level. This exercise involved both uprating the surge protection circuitry, using different components and changing the physical layout of parts of the embedded electronics system.

    To speed the design phase, Abriox constructed its own simple low-power generator that could provide a high voltage pulse, to test switching times and clamping characteristics. However, when the final protection design was settled on, Abriox took a monitor to Cobham to fully characterise its performance against lightning pulses.

    Cobham subjected the equipment to increasing levels of lightning strikes using a range of pulse shapes and durations that represented the kind of surges that would be experienced in typical installation scenarios. The revised protection worked perfectly, and continued to operate successfully beyond its target energy level protection rating corresponding to a 12 kA transient waveform. Cobham used a 30 kA-rated generator to test the equipment, and in the very final test step, the strike energy was increased to the maximum. Although this destroyed the front-end protection circuitry, the Merlin monitor itself survived and continued to function.

    "With Cobham's help, we now know exactly what our lightning protection system is capable of," adds Jason Hanlon of Abriox. "It's impossible to protect against every conceivable lightning strike, but we know that our equipment will be resilient when faced with the majority of the real-world energy surges that could be encountered."

    "This particular project was very interesting. Our understanding of the nature of the lightning threat means that we were able to simulate the type of waveform expected by Abriox's monitor in the field," says Dan Brown of Cobham Technical Services. "This type of pipeline installation makes it highly likely that power surges arrive indirectly, from the pipe or power supply, making it important to consider protection for the design as a whole - rather than just the system inputs. It's easy to blow up a device in our lab; what's more of a challenge is to do it in a representative way."

     

  • Lightning protection - Pre-empting the strikes

    Many organisations seeking to lower their carbon footprint are tapping into solar energy using photovoltaic systems, which are highly vulnerable to lightning damage. Ian Langeveld, UK and Ireland sales manager with Wieland Electric, discusses the importance of suitable protection for these systems

    As technology has become an integral part of everyday life, measures to protect our devices and the systems that serve them have also increased in importance. Indeed, in some cases, protecting these systems has become critical to the business’s ability to operate. Thus, for example, protection against the damage that can be caused by lightning strikes is now just as important for many businesses as securing their buildings against intruders.

    Now, with the growing use of photovoltaic (PV) arrays to harness solar energy there is an additional area to be considered when it comes to protection strategies. And with feed-in tariffs encouraging electricity generation from renewable energy sources this is an area that will continue to grow.

  • Power supplies survive lightning strike test

    DIN-rail power supply manufacturer PULS has carried out extreme testing of its QT40 3-phase units by subjecting them to simulated lightning strikes.

  • Lightning current and surge arrester for multi-pair telecom cabling

    In today’s modern world the uninterrupted use of information technology and automation equipment is taken for granted. Lightning discharges, surges and over-voltages can cause major problems to equipment resulting in physical damage, data loss and the associated cost of lost production.

  • Lightning and surge protection for intrinsically safe circuits by DEHN (UK) Ltd

    In chemical, petrochemical and many industrial plants, potentially explosive areas develop frequently during the manufacturing, processing, storage, and transportation of flammable materials (e.g. gasoline, alcohol, liquid gas, explosive dust).

    Special explosion protection measures must be taken in industrial sectors where gas, vapour, fog or dust occurs during the processing or transport of flammable substances which, in combination with a mixture of air, may present a dangerous explosive atmosphere.

    Lightning currents and overvoltages in potentially explosive atmospheres

    When assessing the risk for potentially explosive atmospheres, the following lightning related ignition sources should be considered:

  • Lightning and surge protection for photovoltaic (PV) systems

    Due to their exposed installation sites and large collection areas, Photovoltaic (PV) installations are at a high risk of damage due to both direct and indirect lightning strikes. Since the PV system is connected directly to the building electrical system, the subsequent damage and disruption from these surges can cause serious damage to PV installations, expensive inverters and the building electrical system. Damage is not only limited to potentially high repair costs but also loss of service and important revenue for Solar Power plants.

  • Decreased downtime

    Transient surges are a change in fundamental frequency that occur thousands of times a day when using a VFD (variable frequency drive). Standard surge protection devices are voltage triggered only and do not account for these transient surges that can lead to confusion in electrical systems. Examples include false zero crossing, false triggering of diodes and timing issues.

  • Changes to 18th Edition

    With the introduction of the 18th Edition the decision-making process for inclusion of overvoltage protection in electrical installations has changed. Here, Dave Enefer, devices product manager at Crabtree, looks at the latest requirements for overvoltage protection.

  • New rules

    Gary Parker, senior technical support engineer, ECA, takes a closer look at surge protection and the changes made to the 18th Edition.

  • Surging ahead

    The growing sophistication of today’s electronic equipment calls for more stringent safety measures. Helen Johnson, technical sales director, Surge Protection Devices Ltd, discusses the levels of lighting and surge protection required in order to meet the new British and European Standard, BS EN 62305. 

  • Get protected

    SELECT's Dave Forrester offers some tips on how to protect gadgets from surges caused by lightning strikes.